Method of obtaining bicarbonate of soda.



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NOAH WRINKLE AND ROBERT G. PADDOCK, OF SAN FRANCISCO, CALIFORNIA, ASSIGN- ORS TO NATURAL SODA PRODUCTS COMPANY, OF SAN FRANCISCO, CALIFORNIA, A

CORPORATION OF CALIFORNIA.

METHOD OF OBTAINING BICAREONATE OF SODA.

No Drawing.

Specification of Letters Patent.

Patented A11 8, 1911.

Application filed May 23, 1910. Serial No. 562,898.

county of San Francisco and State of Cali fornia, have invented new and useful Improvements in Methods for Obtaining Bicarbonate of Sodzuot'. which th c following is a specification.

Our invention relates to methods for obtaining acid carb onate of soda \vhi h is commonly KUOWII a. bi-carbonate o't' soda, and has for its object to provide a process for obtaining bi-carbgmate of soda, of a. grade approximately chemically pure, for commercial purposes, from waters of certain lakes which contain both acid and normal carbonates of soda, the normal being in excess; and also various contaminating substances, as sodium chlorid and sulfate in solution, and organic matter in suspension; and we accomplish our objects by a novel series of steps, arranged to obtain the results desired with improved etliciency and economy.

In broad terms, our invention consists, first, in freeing the waters of substances in suspension by filtration. and thereafter of causing by evaporation the normal andacid carbonates to unite and crystallize out in the form of urao, leaving the cxccss oi' normal carbonate and the contaminating salts in the mother liquor, separating'and dis solvin; the urao and treating the same with carbon dioxid, to change the normal carbonate into acid carbonate, separating all but about ten per cent. of theaicid carbonate l'rom the liquor, and uniting the mother liquor of the carbonating step with the lake waters, that are being evaporated to form an increased quantitv ol urao.

llxplaiuing the steps of our process in detail. we first Htlbjttl. the lake water to liltration. to separate the suspended matter,

which usually consists of or; amc remains.

'c then )l'ol'ccd to cva ioratc the tilhu-od solution. the objectbeing to .t| :ll'ntt thef acid and normal carbonates l'rom the con- This separation takcsi laminating salts. place when the solution attains a density ol' 332 degrees liuumc. at a temperature above Ht)" l' ahrenhcit. [)Itnllltttl in the olution by solar heat, which we use as the evaporating agent. At the aforesaid density, and in the presence of sodium chlorid, acid carbonate and normal carbonate will unite to form urao, and the urao will crystallize and precipitate. The urao referred to is a compound, sometimes called natural soda, having approximately the chemical formula The contaminating salts remain in the mother liquor. as does also the excess of normal carbonate; and we draw off the mother liquor before increasingdensity causes the deposition of the contaminating salts a'toresaid. Having: separated the urao from the contaminating salts, we next dissolve the nrao in fresh water, to form a solution of urao. The aforesaid solution is then subjected to a treatment of carbon dioxid gas under pressure for the purpose of converting the normal carbonate into ac d carbonate. \Ve next separate the crystals of bicarbonate of soda. from the solution, which retains in solution about ten per cent. of bicarbonate oi? soda. But the etliciency of our process is further increased by the next step. which consists in combining the lake waters undergoing evaporation with the mother liquor of the carbonating operation; and since the lake water contains normal carbonate of soda. and the mother liquor from the carhonatin operation contains acid carbonate of soda, their union forms the compound urao from which more acid carbonate may be and is manufactured in the same manner as above described.

in applying our process tothe deposits left on the lake shores by the recession of the waters. we dissolve the deposits by adding waters trom extraneous sources and treat the solution in the same manner as the natural waters, that is, by combining the mother liquor from the carbonating op erat'ion with suitable quantities of the solutions the mother liquor from the evaporatin; operation, or with the fresh solutions, or with admixtures of fresh solutions. ln

cariw'iugout thcstepsot the process We construct dikes out of the clay which abounds in the vicinity, int-losing the deposits in vats, basins or other containers wherein the solutions may be treated se arately.

Having rlvsm'ihed our invention what We 'lnii'n as new urnl (lash-0 to swore by Letters lutvnt of tho li'nitml States is:

The znothod for obtaining bicm-bonate of smln fol. (:mun'inrviul purpmjw t'oin waters containing zwitl .lDll normal (zu'lu nt'os of sotln. tho normal being in exvess, orgunio matter in s|it p(-iisio1i mu! sodium chlorid and sulfate in solution, \Yllilrh comlts in 'ti'eeing' the waters of the suspended orgunic nmttm: by filtration, evaporating the waters by s lar heat to extract tlici'e't'rt'nn umo in sutlicicnt' zuuount to exhaust the said acid t-m'hoi-mtu (*oinprmenti. l ning in the solution the JXULHQ 0t" normal carbonate, wpuinting the iu'no from the mother liquor iliwzlving tlu? iu'uo infrcsh miter, CurlJ 0nuting the solution of uruo to form acid :zu'bonutie of soda from the normal carbonl p i t l l I :ito vonstit'twnt, depositing: and recovering all hut nhout; ten pen Pent. offbeat-id carbonuto from the solution, and uniting said solution with :1 further quantity of the said waters that are being t-vnpol'nt'ml. to form 2L groutur quantity of 111110 than would result l'ioni evaporation of wntm' not so treated. In witness wluri'ooi we have, wu'h of us tor lllHlStl'll. hcrgunto signed our YHIEHOS, in the presenvc of the witnesuos whose signatures as HIHl] witnesses are hereunto Suhsvlihml. in the ('ity and county of San Francisco and State of California this 22d (lay of Min-0h, in the your 1010.

NOAH \Y HNKLE. ROBERT (E. PADDOCK. In tho presence (ff-- P. .1. ()Dm, FRANK P. .lvitnmxA. 

